Whale populations were drastically reduced in the 20th century from intensive whaling, and the activity was globally banned in 1982.[7] Smaller cetaceans are at risk of accidentally getting caught by fishing vessels using, namely, seine fishing, drift netting, or gill netting operations.[8]

The following is a list of existing (extant) species of the infraordercetacea, organized taxonomically into parvorders, superfamilies when applicable, families, subfamilies when applicable, genus, and then species. In tabular form, seven descriptors are given for each species: the common name; the scientific name; the IUCN Red List status; a global population estimate; a global map with its range; its weight with an image of its shape, and its size relative to a human; and a photograph.

Where available, the global population estimate has been listed. When not cited or footnoted differently, these are from the IUCN Red List of Threatened Species (v. 2014.3; data current at 20 January 2015).[9]

The baleen whales, also called whalebone whales or great whales, form the Mysticeti. Baleen whales are characterized by having baleen plates for filter feeding and two blowholes. During the embryonic phase, Mysticetes do have teeth but they are reabsorbed before birth.[10]

The family Balaenidae contains two genera and four species. All the Balaenidae whales have no ventral grooves; a distinctive head shape with a strongly arched, narrow rostrum, bowed lower jaw; lower lips that enfold the sides and front of the rostrum; long, narrow, elastic baleen plates (up to nine times longer than wide) with fine baleen fringes; and fused cervical vertebrae rendering the head immobile.[11]

Rorquals are the largest group of baleen whales, with nine species in two genera. They include the largest animal that has ever lived, the blue whale, which can reach 190 tonnes, the fin whale can easily reach 50 tonnes, and even the smallest of the group, the northern minke whale, reaches 9 tonnes. They take their name from a Norwegian word meaning "furrow whale": all members of the family have a series of longitudinal folds of skin running from below the mouth back to the navel (except the sei whale, which has shorter grooves). These are understood to allow the mouth to expand immensely when feeding.[13] All rorquals have ventral grooves, and are the only cetaceans to have them. Additionally, they all have dorsal fins, broad, gently curving rostra and short baleen plates.[11]

The pygmy right whale shares several characteristics with the right whales, although having dorsal fins separates them from right whales, and they have a very distinctive jaw configuration. Pygmy right whales' heads are no more than one-fourth the size of their bodies, whereas the right whales' heads are about one-third the size of their bodies.[11] The pygmy right whale is the only extant member of its family, otherwise better characterized by the extinct genus Cetotherium.

The gray whale has been placed in a family of its own, as it is sufficiently different from the right whales and the rorquals. The gray whale is the only benthic feeding baleen whale, filtering small organisms from the mud of shallow seas. They also have a gestation period of over a year, which is unusual for baleen whales.[11]

Oceanic dolphins are the members of the cetacean family Delphinidae. These aquatic mammals are related to whales and porpoises. As the name implies, these dolphins tend to be found in the open seas, unlike the river dolphins, although a few species such as the Irrawaddy dolphin are coastal or riverine. Six of the larger species in the Delphinidae, the killer whale (orca) and its relatives, are commonly called whales, rather than dolphins. They are also sometimes collectively known as "blackfish".

The Delphinidae are characterized by having distinct beaks (unlike the Phocoenidae), two or more fused cervical vertebrae and 20 or more pairs of teeth in their upper jaws. None is more than 4 m long.[11]

The cetacean family Monodontidae comprises two unusual whale species, the narwhal, in which the male has a long tusk, and the white beluga.

The Monodontidae lack dorsal fins, which have been replaced by tough, fibrous ridges just behind the midpoints of their bodies and are probably an adaptation to swimming under ice, as both do in their Arctic habitat. The flippers are small, rounded and tend to curl up at the ends in adulthood. All, or almost all, the cervical vertebrae are unfused, allowing their heads to be turned independently of their bodies. None has any throat grooves.[11]

The dwarf and pygmy sperm whales resemble sperm whales, but are far smaller. They are dark gray, dorsally, while ventrally they are lighter. They have blunt, squarish heads with narrow, underslung jaws; the flippers are set far forward, close to the head and their dorsal fins are set far back down the body.

Porpoises are small cetaceans of the family Phocoenidae. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen. The most obvious visible difference between the two groups is porpoises have spatulate (flattened) teeth distinct from the conical teeth of dolphins. In addition, porpoises are relatively r-selected compared with dolphins: that is, they rear more young more quickly than dolphins. All seven species have small flippers, notched tail flukes, and no beaks. All carry at least 11 pairs of small teeth in their upper and lower jaws.

Porpoises, divided into seven species, live in all oceans, mostly near the shore. Probably best known is the harbour porpoise, which can be found across the Northern Hemisphere.

The sperm whale characteristically has a large, squarish head one-third the length of its body; the blowhole is slightly to the left hand side; the skin is usually wrinkled; and it has no teeth on the upper jaw.

A beaked whale is any of at least 22 species of small whale in the family Ziphiidae. They are one of the least-known families of large mammals: several species have only been described in the last two decades, and it is entirely possible that more remain as yet undiscovered. Six genera have been identified.

They possess a unique feeding mechanism known as suction feeding. Instead of catching their prey with teeth, it is sucked into their oral cavity. Their tongue can move very freely, and when suddenly retracted at the same time as the gular floor is distended, the pressure immediately drops within their mouth and the prey is sucked in with the water. The family members are characterized by having a lower jaw that extends at least to the tip of the upper jaw, a shallow or non-existent notch between the tail flukes, a dorsal fin set well back on the body, three of four fused cervical vertebrae, extensive skull asymmetry and two conspicuous throat grooves forming a 'V' pattern.[11]

River dolphins are five species of dolphins which reside in freshwater rivers and estuaries. They are classed in the cetacean superfamily Platanistoidea. Four species live in fresh water rivers. The fifth species, the La Plata dolphin, lives in saltwater estuaries and the ocean. However, it is scientifically classed in the river dolphin family rather than the oceanic dolphin family. All species have adaptations to facilitate fish catching: a long, forceps-like beak with numerous small teeth in both jaws, broad flippers to allow tight turns, small eyes, and unfused neck vertebrae to allow the head to move in relation to the body.

The family Lipotidae is another monotypic taxon, containing only the baiji. Fossil records suggest the dolphin first appeared 25 million years ago and migrated from the Pacific Ocean to the Yangtze River 20 million years ago.[18] The species was declared functionally extinct in 2006 after an expedition to record population numbers found no specimens.

The Platanistidae were originally thought to hold only one species (the South Asian river dolphin), but based on differences in skull structure, vertebrae and lipid composition, scientists declared the two populations as separate species in the early 1970s.[19] In 1998, the results of these studies were questioned and the classification reverted to the pre-1970 consensus. Thus, at present, two subspecies are recognized in the genus Platanista, P. gangetica minor (the Indus river dolphin) and P. g. gangetica (the Ganges river dolphin).[20]

The La Plata dolphin is the only species of the family Pontoporiidae and genus Pontoporia. These dolphins are known for their long beak in relation to their relatively small body size. They have a small geographic range and are mainly found in the waters along the east coast of South America. La Plata dolphins are exclusively marine organisms, however, they are grouped with river-dolphins due to the fact that they reside in the La Plata River which is a salt-water estuary. With their white or sometimes pale brown coloration, fishermen tend to call them "the white ghost", as they also tend to stray away from any human interaction. [21]

^As of August 2018, the Society for Marine Mammalogy considers the long-beaked common dolphin as an ecologically-induced form of the short-beaked dolphin based on molecular evidence. The Eastern North Pacific long-beaked dolphin population may be a unique species D. bairdii[14]

^The total population is unknown but numbers in the hundreds of thousands

^The only population estimate is of 38,900 individuals in the eastern tropical Pacific Ocean

^Total population is not known. There are estimated to be in excess of 200,000 in the Southern Ocean. The North Atlantic population is not known

^Total population not known. There are 150,000 individuals in the eastern tropical Pacific Ocean. There are estimated to be more than 30,000 animals in the western Pacific, off the coast of Japan

^The population around the continental shelf of the United States has been recorded to be in excess of 60,000. In the Pacific, a census recorded 175,000 individuals in eastern tropical waters and 85,000 in the west. No global estimate of population exists

^Total population unknown but thought to be locally common – it is the most common dolphin found around the Falkland Islands

^Estimates of various stocks throughout the North Atlantic give an overall value into the high tens or low hundreds of thousands

^Varying population estimates for areas around California and the North Pacific give a total of up to 400,000

^Surveys suggest this is the most common dolphin off of Chilean waters

^Local estimates include 70–80,000 in the Antarctic, 8,000 in the tropical Pacific (although tropical waters are not the orca's preferred environment, the sheer size of this area — 19 million square kilometres — means there are thousands of orcas), up to 2,000 off Japan, 1,500 off the cooler northeast Pacific and 1,500 off Norway

^Estimates for eastern tropical Pacific are 45,000 and another recent survey estimates population to be 1,200 for the eastern Sulu Sea, no global estimate is known

^The total population is unknown. The eastern Pacific was estimated to have in excess of 40,000 individuals and is probably the home of the largest grouping

^As of August 2018, the Society for Marine Mammalogy does not consider the Burrunan dolphin a distinct species due to problematic methodology in the study proposing its classification. The organization recommends further study to determine its validity.[14]

^There are estimated to be 40,000 individuals in the Beaufort Sea, 25,000 in Hudson Bay, 18,000 in the Bering Sea and 28,000 in the Canadian High Arctic. The population in the St. Lawrence estuary is estimated to be around 1000

^Aerial surveys suggest a population of around 20,000 individuals. When submerged animals are also taken into account, the true figure may be in excess of 25,000

^No global population estimates have been made. One survey estimated a population of about 11,000 in the eastern Pacific

^No global population estimates have been made. One survey estimated a population of about 11,000 in the eastern Pacific

^There is not enough data to place finless porpoises on the endangered species list

^There are no good estimates of the animals' abundance. However a comparison of two surveys, one from the late 1970s and the other from 1999/2000 shows a decline in population and distribution

^In China, they are endangered. Their propensity for staying close to shore places them in great danger from fishing

^Nothing is known of the abundance of this porpoise. It was the most commonly encountered species during preliminary beach surveys undertaken on Tierra del Fuego

^The most recent estimate for the North Pacific and Bering Sea is 1,186,000

^The total number of sperm whales throughout the world is unknown. Crude estimates, obtained by surveying small areas and extrapolating the result to all the world's oceans, range from 200,000 to 2,000,000 individuals

^Arnoux's beaked whales seem to be relatively abundant in Cook Strait during summer

^Virtually nothing is known about the abundance of Baird's beaked whales, except they are not rare as was formerly thought

^Nothing is known about the relative abundance of this species or its population composition

^Because of the difficulty of identifying the species the total global population is unknown